1. Field of the Invention
The present invention relates generally to flexible tubing functioning as conduits for electrical wires and more particularly to fittings adapted for connection to the ends of the flexible tubing.
2. Description of the Prior Art
Flexible tubing suitable for housing electrical wiring usually comprises a spirally wound wire encapsulated within a strip of resilient plastic or rubber. The plastic strip is also spirally wound in an overlapping manner, with the overlaps being bonded to form a continuously sealed cylindrical conduit. Because of the spiral construction, the tubing is capable of bending and twisting when in use. The resilient plastic or rubber material also enables the tubing to contract and expand longitudinally. These many degrees of freedom of movement are a distinct advantage during installation and also during operation, especially when such tubing is utilized to interconnect relatively movable parts.
The main problem involved in using flexible tubing lies in connecting this type of tubing with junction boxes. Heretofore, the tubing was usually threaded into bores formed in the boxes, the threads being formed by the outer surface of the spirally wound wire and plastic coating. The shortcoming with this method of connection is that the tubing end would frequently work itself out of the box bore during operation, thereby exposing the electrical wires contained therein.
Another method of connecting the ends of the tubing to the bores of the junction boxes would be to utilize thread washers onto the ends of the tubings after they were extended through the box bores. This, however, did not solve the problem because the tubing could still work itself out of the washer during operation. The reason for this is that the tubing was able to twist and the threads were able to contract during operation. As a result, the tubing was not able to remain in tight frictional contact with the threaded connections.